Shiite religious leader Mohammed al-Fartussi threatened "sinful women," alcohol sellers and cinemas of grave consequences if they did not stop their practices within a week.
"The cinemas in Al-Saadun Street show indecent films. I warn them: if in a week they do not change, we will act differently with them," he said in a sermon at Muslim weekly prayers at Al-Mohsen mosque in Baghdad's Shiite surburb of Sadr City.
"We warn women and the go-betweens who take them to the Americans: If in a week from now they do not change their attitude, the murder of these women is sanctioned (by Islam)," Fartussi added.
"This warning also goes out to sellers of alcohol, radios and televisions," the imam, or prayer leader, told a crowd of several thousand faithful.
"The torching of cinemas would be permitted" by Islam unless they changed their behavior, Fartussi said.
The Shiite cleric was detained for three days last month by US forces controlling Baghdad, and thousands of Shiites demonstrated in the Iraqi capital to demand his release.
"We will not brook any government that does not represent public opinion," he added, saying Iraq should be governed by religious leaders, not "secular parties."
The faithful at both Al-Mohsen and Kazimiya mosques in Baghdad were also urged to take part in peaceful marches planned for Monday.
"We urge all residents of Baghdad to demonstrate peacefully on Monday, to go to mosques, churches and other religious sites," Imam Khaled al-Kadami told thousands of faithful at the main mosque of the predominantly Shiite district of Kazimiya.
Kadami too said religious leaders were well placed to govern Iraq.
"All Iraqis are devout. Iraq is by nature a religious country, and we reject secular parties," he said.
Fartussi, meanwhile, announced that a special religious committee had been set up to collect items stolen during the wave of looting that swept Baghdad after it fell to US forces on April 9 and Saddam Hussein's regime collapsed.
He warned that looters who did not return their booty would be publicly named during Friday prayers and prosecuted.